Exemplary embodiments of the present invention relate to a semiconductor design technology, and more particularly, to a semiconductor integrated circuit and a method for driving the same.
In general, a semiconductor integrated circuit is provided with a redundancy memory cell in addition and performs a repair operation for replacing a defective memory cell with the redundancy memory cell in order to achieve a high yield. The repair operation may be performed by a fuse circuit. For example, the repair operation may be performed by using a method of cutting a fuse by flowing over-current to the fuse, blowing out a fuse by using a laser beam, connecting a cut fuse by using a laser beam, or programming a fuse by using an erasable programmable read only memory (EPROM). Here, the method of blowing out the fuse by using the laser beam is widely used since it may be simple and have much reliability in blowing out the fuse.
However, the method of blowing out the fuse by using the laser beam may be performed only in a wafer state before a semiconductor memory device is packaged. Thus, a method of using an anti-type fuse (Hereinafter, referred to as an ‘anti-fuse’) has been introduced.
The method of using the anti-fuse may be used to replace a defective memory cell with a redundancy memory cell in a package state. For reference, the anti-fuse has an electrical characteristic opposite to the fuse. In detail, the anti-fuse is a kind of resistive element to have a high resistance, higher than or equal to 100 MΩ, in an un-programmed state and to have a low resistance lower than 100 KΩ in a programmed state. That is, when the anti-fuse is implemented with a transistor whose source and drain are electrically connected, the anti-fuse may serve as a capacitor in the un-programmed state and a resistor in the programmed state.
The anti-fuse, as a thin insulation material, may include two conductive layers and an insulation layer therebetween. Here, the insulation layer may include a silicon oxide (SiO2), silicon nitride (SiN), tantalum oxide (TaOx), or silicon dioxide-silicon nitride-silicon dioxide (ONO). A program operation on the anti-fuse is performed by applying a high voltage, e.g., approximately 10 V, to two conductive layers of the anti-fuse, thereby breaking down the insulating properties of the insulation layer therebetween. Accordingly, when the anti-fuse is programmed, two terminals coupled to the two conductive layers of the anti-fuse are short so that the anti-fuse has a low resistance.
However, when a program operation is performed on a plurality of anti-fuses, some of the anti-fuses may not be programmed. This is because it is difficult to manufacture all the anti-fuses to have an identical characteristic. Thus, even if the plurality of anti-fuses is simultaneously programmed, some of the anti-fuses may be ruptured before the others are programmed. At this time, a path of leakage current is formed from a high supply voltage terminal to a low supply voltage terminal, and thus, a voltage level of the high supply voltage terminal may drop.
Furthermore, whenever any of the plurality of anti-fuses is ruptured, the voltage level of the high supply voltage terminal may drop more seriously. If the voltage level of the high supply voltage terminal drops below a rupture tolerance range, the program operation may end in the state that some anti-fuses may not be programmed. For reference, since a high supply voltage is generally generated inside a semiconductor integrated circuit, there may be a limit in maintaining the voltage level of the high supply voltage terminal at a target voltage level when the high supply voltage is used at the same time.
As a result, when a program operation is performed on a plurality of anti-fuses, there may be some anti-fuses whose program operation is not properly performed due to a path of leakage current formed between a high supply voltage terminal and a low supply voltage terminal.